The present invention concerns a method of and device for operating an arc furnace with two vessels, I and II, especially for making steel. Both vessels have lids. There are electrodes on one lid, which pivots. The furnace has lances for injecting oxygen, lime, coal, and gaseous or liquid fuels. To carry out the method, the supply of electricity to one of the vessels, which is charged with starting metallurgicals and covered with a lid, is discontinued but not the supply to the other vessel, which proceeds to carry out metallurgical processing, melting or superheating, for example, until it is time to tap the melt.
Several methods of producing raw steel are known. They proceed by the classic route of blast furnace and converter and mainly use a hot liquid mixed with scrap, oar, sponge, and other starting metallurgicals. The vessels, electric-arc furnaces, mainly use cold or heated starting materials.
Electric-arc furnaces are mainly employed and operated individually.
Systems have been developed recently, however, that, due to the increasing scarcity of natural resources, are intended to ensure steel production that is cost-effective and environmentally friendly.
Among these known approaches is one that employs hot flue gases pumped out of the furnace itself to preliminarily heat the charge, usually scrap, in an electric-arc furnace.
A melting system comprising two adjacent vessels is known from European Patent 0 483 322. It is equipped with a heater to supply energy for heating the melt. Each vessel has a lid, two ports, and gas lines. The gas lines can be blocked. Each port in one vessel communicates with a port in the other vessel through one of the lines. The gas generated when material is melted in one vessel can accordingly be conveyed to the other to preliminarily heat the starting material therein. One outer section of the lid in one furnace can be replaced by a shaft secured in a framework. The shaft has a gated opening at the lid for loading starting material and contains the port associated with that furnace.
A method of and device for operating a two-furnace plant is known from German 4 302 285. The device is in two parts and intended for melting steel. The method is in several steps.
Electricity is supplied to one of the furnaces to melt the scrap accommodated therein. The other is disconnected from the network. The disconnected furnace is tapped and charged with new material, mainly scrap. The lid is replaced. Any gas inside the vessel is pumped out from above the bed of scrap. Flue gas is then pumped out of the electrically connected furnace and into the disconnected furnace. The flow of flue gas from the other furnace is discontinued to allow the gas to be cleaned while the flue gas is being pumped out of the disconnected furnace.
How much raw iron can be used in arc furnaces is limited because pig takes so long to melt. Furthermore, it has until now been impossible to satisfactorily process (decarbonize) liquid raw iron in electric-arc furnaces.
The two known two-furnace plants are in no way appropriate for or even intended for processing liquid raw iron, especially in large batches that can account for more than half of the metallurgical material employed.